PRK is the procedure done with the excimer laser to reshape the cornea and correct the vision. It has fewer complications as compared to LASER. Unlike LASER, the PRK procedure does not require the formation of a corneal flap thereby reducing the complications related to corneal flap. PRK was the first procedure for correcting the curvature of cornea which was approved by US FDA
2. Pro What is
PRK?
PRK ( photorefractive keratectomy ) is
a type of laser vision correction
procedure to correct the refractive
errors that is… myopia, hypermetropia
and astigmatism. PRK was one of the
earliest laser eye surgery vision
correction procedures and has been
performed longer than LASIK which
has become more popular than PRK
now. Similar to LASIK and other types
of LVC procedures corneal reshaping
is done using an EXCIMER LASER thus
allowing the light rays to properly
focus on the retina and achieving a
clear vision without spectacles.
3. WHAT IS THE DIFFERENCE
BETWEEN LASIK AND PRK
In both the techniques the laser used is same and corneal reshaping is also the same
but the difference lies in the FIRST step. In LASIK in the first step a flap is made either
using a microkeratome or a laser , the thickness of the flap varies between 90 to 130
microns and after the procedure is over this flap is repositioned back. In PRK the flap is
not made, instead most superficial layer of the cornea called epithelium ( only 45 to 50
microns thick ) is scrapped /removed to expose the deeper corneal layers which is then
treated with excimer laser to reshape the cornea. The epithelium regrows and repairs
itself within a span of 3 to 4 days 1after the surgery. So PRK is a flapless technique and
since the flap is not made, the tissue saved adds to the residual corneal stromal bed
thickness thus making PRK a very safe procedure in terms of long term corneal
biomechanical stability.
4. Who are the best candidates for
PRK?…in other words what are the
indications for PRK
Patients having relatively thin corneas where lasikcan not be done. In
patients with thinner corneas making a flap ( in the first step of lasik )
may weaken the cornea later on thus it is better to avoid lasik in these
patients and PRK is a preferred procedure.
All those patients who are into contact sports etc , here a possible later
trauma to the flap is theoretically avoided.
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